ARTIFICIAL SPAWNING OF HERBIVOROUS FISH: USE OF AN LHRH-A TO INDUCE OVULATION IN GRASS CARP CTENOPHARYNGODON IDELLA (VALENCIENNES) AND SILVER CARP HYPOPHTHALMICHTHYS MOLITRIX (VALENCIENNES)
E. Brzuska-1999
Aquaculture Research, 30: 849-856
Ovulation was stimulated in females of grass carp Ctenopharyngodon idella (Valenciennes) and silver carp Hypophthalmichthys molitrix (Valenciennes) using LHRH-a with pimozide at doses of 15 mg/kg and 5 mg/kg body weight respectively. The results of reproduction after the LHRH-a stimulation were compared with the results of spawning recorded in the case of hypophysation. In the case of grass carp treated with LHRH-a, the percentage of stripped females was higher than that recorded after hypophysation, while the female of silver carp yielded eggs irrespective of the type of applied ovulation stimulator. The average weight of eggs (in grams and as a percentage of female body weight) obtained from both grass carp and silver carp did not differ significantly in the groups treated with LHRH-a and carp pituitary. Average percentages of fertilization and of live embryos did not differ significantly in the groups treated with the two ovulation stimulators. This statement concerns the two species investigated. Statistically significant differences (P < 0.05) were calculated with respect to the mean percentage of deformed larvae. This percentage was distinctly higher after an LHRH-a treatment in both grass carp and silver carp. Irrespective of the applied ovulation stimulator, a greater weight of eggs of better quality was obtained from silver carp females.
(Polish Academy of Sciences, Institute of Ichthyobiology and Aquaculture Golysz, 43-520 Chybie, Poland)